Railway traffic controlling apparatus



L. R. ALLISON RAILWAY TRAFFIC CONTROLLING APPARATUS Jan. 6, 1942.

5 Sheets-Sheet 1 Filed June 15, 1940 m n Tm N mm m m w A .Q h s m m H 8% \.N\ a If \W v k\ r Jan. 6, 1942. L. R. ALLISON RAILWAY TRAFFIC CONTROLLING APPARATUS 5 Sheets-Sheet 2 Filed June 15, 1940 H15 ATTORN EY Jan. 6, 1942. 1.. R. ALLISON 2,269,238

I RAILWAY TRAFFIC CONTROLLING APPARATUS Filed June 15, 1940 5 Sheets-Sheet 3 mv [\ITOR Lar'lze U012.

HA5 ATTORNEY Jan. 6, .1942. I L. R. ALLISON 2,269,238

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed June 15, 1940 5 Sheets-Sheet 4 ENTOR I Lerlz'e [ll'mn HIS ATTORNEY Jam 1942- L. R. ALLISON 2,269,238

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jfine 15, 1940 5 Sheets-Sheet 5 nun mv more 01119 1- (won.

H15 Ai'TORNEY vals when no current flows.

Patented Jan. 6, 1942 UNITED S'TATE RAILWAY TRAFFIC CONTROLLING APPARATUS Leslie R. Allison,

Union Switch & Signal Company, Pa., a corporation of Pennsylvania Forest Hills, Pa., assignor to The Swissvale, 7

Application June 15, 1940', Serial No. 340,808

19 Claims.

My invention relates to railway, traflic controlling apparatus; and it has particular reference to the or'ganization of such apparatus into railway signaling systems of the class wherein coded track circuit or signaling current is supplied to a shuntable track circuit to control either or both wayside signals and train-carried traffic controlling devices such as cab signals.

It has been proposed heretofore to, supply the rails of a trackway with track circuit current coded at one or another of a plurality of rates of coding in accordance with certain predetermined conditions. Such coding has been effected by periodically interrupting they supply of cur rent to the trackrails to ,provide coded current comprising on intervals, during which current flows, separated from each other by off inter- Equivalent coding has been proposed in certain conditions by utilizing an impedance which is effective to limit the current flow through the impedance to a relatively low value approaching a zero quantity, and by periodically shunting such impedance to increase greatly the current flow, provide a coded current comprising on intervals during which the magnitude of current flowis relatively large due to the shunting of the impedance, and which on intervals are separated from each other by off intervals during which'the impedance is effective to limit the current flow to a relatively low value. In connection with suchcoded current, it had been proposed to employ suitabledecoding apparatus arranged to respond selectively to the different rates at which the on intervals of current occur, for selectively controlling traffic governing devices in accordance with the rate at which such current is coded. Such apparatus usually includes decoding units arranged and tuned to be responsive to but a single or a selected few rates of coding, and it has been proposed to employ a sufficient number of such decoding units each arranged to respond selectively to a different one of the code rates utilized, to enable regarded as desirable,

ber of different controls or functions that can be selectively controlled. I

It has been found advisable in view ofthe vastly increased operating speeds and faster schedules for railway trains recently come to be the number of indications or functions controlled I by the above-mentioned systems utilizing a limthe different rates of coding employed to be distinguished and the traflic 45 current iscoded in the said difierent manner.

controlling devices to be selectively controlled in accordance with such rates of coding. In view, however, of the costs of construction of the decoding units, their size, and other important fac tors, it has been regarded advisable to employ but a relatively few or limited number of differ ent code rates, thereby correspondingly limiting the number of decoding units required This limiting of the number of different code ratesem ployed of course correspondingly limits the numited number of code rates, .may be increased to permit such increased operating speeds by'providing longer braking distances between successivetrains on the stretch or by providing a greater number of proceed indications whereby the speeds at which trainsareoperated can be adjusted more closely to the particular traffic conditions in advance of such trains and to the particular conditions of the ,trackway upon which such trains are operating. .l, In view of the above-mentioned and other important considerations, it is an object of my present invention .to provide novel and improved railway traflic controlling apparatus incorporating means wherewith the usual limited few, code rates of track circuit current'may beutilized to control an increased number vof indications or functions.

Another object of my invention is the provision, in such railway traflic controlling apparatus, of

novel and improved means controlled by predetermined conditions and wherewith theisupply of alternating track circuit current to a trainshuntable track circuit is coded in a particular manner at one or another of the usual. limited number of code rates, and at other times such track circuit current is coded in a distinctively different manner at one or another of" the said limited number of code rates.

An additional object of my invention is. the provision, in such railway traffic controlling apparatus, of novel and improved decoding. apparatus controlled by current received from the rails of the trackway and selectively responsive to, the code rateat which such current is coded in thesaid particular manner and also selectivelyv responsive to the code rate at which such A further object of my invention is the pro-. vision of novel and improved means adapted to A be incorporated into existing signaling systems for increasing the number of functions, selec-. tively controlled by the limited few code rates utilized in such systems.

to provide means whereby The above-mentioned objects, as Well as other characteristic features of my invention which will become readily apparent from the following description, are attained in accordance with my invention by supplying a train-shuntable track circuit with alternating track circuit current which at times is coded in a particular manner at one or another of the limited few rates of coding, and. at other times is coded in a distinctively different manner at one or another of the said rates of coding. The track circuit current is coded in a first manner by apparatus embodying my invention by interrupting periodicab ly the supply of current to provide in the track circuit a coded current comprising on inter vals during which current of a predetermined magnitude flows, separated from each other by off intervals when no current flows. The track circuit current is coded in the other manner by additionally supplying the track circuit during the o intervals of the first-mentioned coded current, with current of a selected value substantially greater than a zero value but also substan tially less than the magnitude of current of the on intervals of the first-mentioned coded current. My invention utilizes the usual decoding apparatus responsive to energy received from a track circuit and arranged to detect the code rates at which the on intervals of coded current of the said predetermined magnitude occur, and it provides additional means responsive to energy received from the track circuit and efiectiveto detect current of the said selected value supplied, when the track circuit current is coded in the second manner, during the off intervals separating successive on intervals of the said predetermined magnitude. The usual and the additional decoding apparatus are arranged to cooperate in selectively controlling a traffic controlling device according as the track circuit current is coded in the first or the second manner and also in accordance with the rate at which such current is coded in either manner. My invention also provides apparatus located in the trackway for controlling the supply of current to the track circuit in accordance with certain predetermined conditions, and such apparatus is arranged also to selectively control wayside signals in accordance with the said predetermined conditions.

Other novel elements and features of my invention reside in the specific construction and arrangement of apparatus and circuits employed, and I shall first describe in detail such apparatus and circuits in the following description of three illustrative forms of apparatus embodying my invention, and shall then particularly point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1A, 1B, 1C and 1D when placed end to end in the order named, with Fig. 1A on the left, constitute a diagrammatic view showing the trackway portion of a preferred form of apparatus embodying my invention.

Fig. 2 is a diagrammatic view illustrating the train-carried portion of a preferred form of apparatus embodying my invention and adapted to cooperate with the trackway apparatus represented in Figs. 1A to 1D, inclusive.

Fig. 3 is a diagrammatic view showing a modified form of the trackway apparatus represented in Figs. 1A to 1D, and which also embodies my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Figs. 1A, 1B, 1C and 1D, the

reference characters I and la designate the track rails of a stretch of railway track over which traific normally moves in the direction indicated in the drawings by an arrow, and which I shall assume to be the eastbound direction. The rails I and la are divided by means of the insulated track joints 2 into a plurality of successive adjoining track sections J-K, KL, etc.

Each of the represented track sections is provided with a group of traffic controlled'relays comprising a polarized track relay, designated by the reference character TR with a suitably distinguishing suffix, and. two polarized line relays, designated respectively by the reference characters AR and BR with suitably distinguishing sufiixes.

Each of the represented track sections of Fig. 1 is provided also with a track circuit formed by connecting the winding of the associated track relay TR across the rails of the section adjacent the entrance end and connecting a suitable source of unidirectional track circuit current across the rails of such section adjacent the exit end over pole-changing contactscontrolled by the track relay of the section next in advance. Referring to section J-K, for example, the rails of this section are supplied with unidirectional track circuit current of what I shall term normal polarity by a circuit extending from the upper terminal, as viewed in Fig. 1A of the drawings, of a suitable source of unidirectional current, such as battery 4, through front contact 5 of relay TRK of section KL immediately in advance, or to the right as viewed in the drawings, of section J-K, and a current limiting impedance 6 to rail I, and which circuit extends from the lower terminal of battery 4 through front contact I of relay TRK and a secondary winding 8 of a track transformer TTK, later to be referred to, to rail Ia. It is readily apparent that if relay TRK is released, the upper terminal of battery 4 then is connected through back contact II of relay TRK to rail I a and the lower terminal of battery 4 is connected to rail I through back contact ID of relay TRK, and the polarity of current supplied from battery 4 to the rails of section JK when relay TRK is released is the reverse of that which is supplied when relay TRK is picked up. It follows, therefore, that the polarity of unidirectional track circuit current supplied to the rails of a section is controlled by the track relay of the section next in advance and is of normal or reverse polarity according as such advance relay is picked up or released. Each track relay TR when energized with current of normal polarity operates its polar contact members to the normal or, as viewed in Fig. 1, right-hand position, and when energized with current of reverse polarity operates its polar contact members to the reverse or left-hand position.

The two polarized line relays AR and BR provided for each section are each controlled through the medium of an associated pair of conductors included in a line circuit controlled by the group of traffic controlled relays of the section next in advance. Referring again to section JK, for example, relay ARJ is shown provided with an energizing circuit which extends from one terminal B of a suitable source of current, such as a battery not shown, through front contact I2 of relay ARK, wire I3, normal polar contact I I-J5 of relay TRK, conductor IS, the winding of relay ARJ, conductor I1, front contact I8 of relay TRK, wire I9 and front contact 20 of relay ARK to the other terminal C of the source of current, and relay ARJ accordingly is energized by current of what I shall term normal polarity to operate its polar contact members to the normal or right-hand position. When relay ARK is released and the circuit for relay ARJ is closed at all other points, current of reverse polarity is supplied to such circuit over back contacts 2| and 22 of relay ARK, these latter contacts of relay ARK functioning to pole change the current supplied to relay ARJ, as can readily be seen from an inspection of the drawings. It follows, therefore, that the polarity of current supplied to each AR relay is controlled by the AR relay of the section next in advance and is of normal or reverse polarity according as the AR relay of the section next in advance is picked up or released.

Relay BRJ of section J--K is provided with an energizing circuit which may be traced from terminal B of the source of current through front contact 24 of relay BRK, wire 25, normal polar contact 2'621 of relay ARK, wire 28, normal polar contact 2930 of relay TRK, conductor 3|, the winding of relay BRJ, wire 32, front contact 33 of relay TRJ, conductor 34, front contact 35 of relay TRK, wire 36, front contact 3! of relay ARK, wire 38, and front contact 39 of relay BRK to terminal C, and relay BRJ accordingly is energized with current of what I shall term normal polarity and consequently operates its polar contact members to the normal or right-hand position. If, however, the BR relay of the section next in advance is released and the just traced circuit is completed at all other points, then relay BRJ is supplied with current of reverse polarity over back contacts 40 and 4| of relay BRK, as is readily apparent from an inspection of the drawings. The polarity of energization of each BR line relay accordingly is controlled by the BR relay of the section next in advance, and each BR line relay is supplied with current of normal or reverse polarity according as the BR relay of the section next in advance is picked up or released.

It should be noted that the line circuit of each AR relay is completed over a closed front and normal polar contact of the track relay TR of the section next in advance, and that the line circuit of each BR relay is completed over a closed front contact of the track relay TR of the same section and over a closed front and normal polar contact of both the track relay TR and the AR relay of the section next in advance. It can be seen, therefore, that when a track relay is re leased or is energized with current of reverse polarity, both the AR and the BR line relays of the section next in the rear are released, and that whenever an AR relay is released or is energized with current of reverse polarity, the. BR line relay of the section next in the rear is released.

Each section is provided with a signal, designated by the reference character S with a suitably distinguishing sufiix, located adjacent the entrance end of its associated section for governing traffic operating thereover. Signals S may take any one of many suitable forms but in the form herein shOWn each comprises two threeindication color light signal units, each unit of which comprises a red lamp R, a yellow lamp Y and a green lamp G. Each signal S is controlled in. a manner to be described in detail presently, by the group of trafiic controlled relays of its associated section.

Each section also is provided with means for supplying its track circuit with alternating track circuit current coded in one or another of two distinctive manners and at one. or another of a plurality of code rates. The trackway apparatus supplying alternating current to each track circuit is locatedat the leaving or exit'end of the associated section, and it includes the usual track transformer, designated by the reference characer TT with a suitably distinguishing suffix, which has its secondary winding 8 connected, in series with impedance 6 and battery 4, across the rails of the associated section adjacent the exit end of such section over front contacts 5 and I or back contacts l0 and H of the track relay TR associated with the section next in ad- Vance. The primary winding 9 of each transformer is supplied in a manner to be explained in detail presently with current from a suitable source of alternating current, such as a generator not shown but having its terminals designated in the drawings by the reference characters BX and CX.

The current that is supplied to each track transformer from the source of alternating cur rent is caused to be codedin a first manner by means of an associated code transmitter, designated by the reference character CT with a suitably distinguishing suffix. These code transmitters may take any one of several suitable forms Well known to the art, and each is characterized by the provision of a plurality of contact-making and breaking members which are constantly opcrated at different rates. As shown in Fig. 1A, transmitter CTK is provided, for example, with three such coding contact members, 15, I20 and Hill, which members are operated alternately to close and to open circuit controlling contacts at, for example, 75, 12 0 and times per minute,

respectively. Each of the plurality of contact 3 members of device CTK is interposed in a different one of a plurality of circuits shortly to be traced in detail and controlled by the traflic con,- trolled relays associated with section K-L, whereby primary winding 9 of track transformer T'IK of section JK is supplied with periodically interrupted or coded track circuit current comprising on intervals during which current of a predetermined magnitude flows, separated from each other by off intervals when no current flows. I shall refer to the type of current present in a track circuit when such current is coded in the above-described first manner, as being codedcurrent.

The second manner of coding the track circuit current may be achieved by supplying to each track transformer, in addition to the first-mentioned coded current, current of a different, lower value coded at the same rate of coding as that of the first-mentioned current but having its on intervals 180 out of phase with the on intervalsof the other code, so that an on interval of the first-mentioned current corresponds with an off interval of the second coded current, and correspondingly an off interval of the firstmentioned current corresponds to an on period of the second current. However, I prefer to code the current in the second manner by utilizing an impedance to limit the current supplied through the impedance to a track transformer, and by ance is effective to limit the current flow to the transformer. Current coded in the above described second manner is supplied to each track transformer TT over one or another of a plurality of circuits shortly to be traced in detail and controlled by the traffic controlled relays of the section next in advance. At this time, however, it should be pointed out that when current coded in the second manner is being supplied to a track transformer, a portion of such current is su plied over a first circuit path which includes the impedance and which is not interrupted by a contact of the associated coder CT, while another portion of such. current is supplied over a second circuit path which shunts the impedance of the first path, and which second path is periodically interrupted by a contact of the coder. To distinguish between the currents supplied over each two circuit paths when current coded in the second manner is being supplied to a track transformer, I shall refer to the current in the path including the contact of the associated coder as being coded or periodically interrupted current since the circuit over which such current is supplied is periodically interrupted due to the opening and closing of the coder contact, and I shall refer to the current in the other path which includes the impedance as being non-coded or uninterrupted current since this path is not interrupted by a coder contact. cnt, therefore, that when current coded in the above-described second manner is being supplied to a track circuit, such current is in effect equivalent to and may be considered as comprising uninterrupted current of a selected value detereration of a slow releasing checking relay, designated by the reference character CR with a distinguishing suffix, and that when a checking relay CE is caused to operate due to the supply of non-coded current to its associated transformer primary winding 9, the supply of coded alternating current to that transformer primary winding is placed under the control of such checking relay. The manner and particular utility of the check made by the checking relays CR upon the supply of non-coded current to its associated transformer primary winding will be explained in detail hereinafter.

As shown in Fig. 1D, the section to the right or in advance of section OP is occupied by a train W. To explain the operation of the trackway apparatus embodying my invention, I shall describe first the manner in which the trackway apparatus associated with each of the sections shown in Figs. 1A to 1D, inclusive, responds to the presence of train W in the section in advance of section OP, to selectively control the associated wayside signal S and the supply of alternating track circuit current to the rails of the section next in the rear, and shall point out later in connection with the apparatus of Fig. 2 the function of each form of the alternating track circuit current supplied to the rails of the various sections.

Under the above assumed conditions, the presence of train W in the section in advance of sec- It is readily appar- 5 tion OP causes track relay 'IRP to be released to open its front contact 33 and thereby open the energizing circuit of relay BRP so that the latter relay also is released. Signal SP is controlled to display its most restrictive or its red over red aspect by an energizing circuit for red lamp R of the upper unit, as viewed in the drawing, of that signal extending from terminal B through back contact 43 of relay BRP, back contact 44 of relay TRP and the filament of lamp R of the upper unit of signal SP to terminal C; and by an obvious energizing circuit for lamp R of the other or lower unit of signal SP completed at back contact l5 of relay TRP. The display of the red over red aspect by signal SP at this time indicates that its associated section is occupied.

With relay TRP released, the rails of the section next in the rear or section OP are supplied over back contacts l0 and H of relay TRP with unidirectional track circuit energy of reverse polarity so that relay TRO of section OP is energized in its reverse direction, and relays ARO and BRO associated with section O'-P are both released since their respective energizing circuits are open at front contacts of relay TRP.

The rails of section OP also are supplied with both '75 code alternating current and uninterrupted alternating current, the latter current being supplied to the rails of section OP through the medium of track transformer TTP which has its primary winding 9 connected in a circuit including a limiting impedance 3 and extending from terminal BX through impedance 3, back contact 45 of relay TRP, the primary winding of a relay transformer TP, and primary winding 9 of transformer TTP to terminal CX. The supply of energy to transformer TTP through the primary winding of transformer TP causes an electromotive force to be induced in the secondary winding of transformer TP, which induced electromotive force is rectified by a rectifier RTP into and is supplied to checking relay CRP as unidirectional energy to hold the latter relay picked up. Alternating current of 75 code is supplied to the rails of section OP over a circuit path which shunts limiting impedance 3 and extends from terminal BX through contact l5cl5 of code transmitter CTP, front contact 41 of relay CRP, back contact 48 of relay TRP and primary winding 9 of transformer TTP to terminal CX. It should be noted that the supply of '75 code track circuit current is carried through closed front contact 41 of relay CRP which is held energized by the supply to the rails of the uninterrupted track circuit current. It follows that under the above-assumed condition of the apparatus, if the uninterrupted track circuit current that is supplied through impedance 3 is cut off for a period longer than the slow release interval of relay CRP, checking relay CRP would be released to interrupt the supply of 75 code trackway energy and as a result the rails of the section no longer would be supplied with alternating trackway energy. The purpose and particular utility of the check made by checking relay CRP upon the supply of uninterrupted alternating trackway energy to the rails of section O--P will be pointed out hereinafter.

In response to the reverse energization of relay TRO, signal SO associated with section OP is controlled to display a red over yellow aspect to indicate that the section next in advance of its associated section is occupied and its associated section is unoccupied, the aspect being displayed in response to an energizing circuit for relay TRO, reverse polar contact 53-54 of relay r TRO and the filament of lamp Y of the lower unit of signal S to terminal C. Also, the rails of section N-O are supplied with unidirectional trackway energy of normal polarity over front contacts and 1 of relay TRO so that relay TRN s energized to close its normal polar contacts. Relays ARN and BRN associated with relay TRN are, however, released since'the polar contact members of relay TRO occupy their reverse positions.

The rails of section NO are supplied with alternating track circuit current of '75 code over a circuit which may be traced from terminal BX through contact a15 of coder CTO, reverse polar contact 5556 of relay TRO, front contact 51 of relay TRO and primary winding 9 of transformer TTO to terminal CX.

With relay TRN'energized by unidirectional current of normal polarity received from the rails of its associated section and relays ARN and BRN released, signal SN is controlled to display a yellow over red aspect over a circuit extending from terminal B through back contact 43 of relay BRN, front contact 49 of relay TRN,

normal polar contact 59--69 of relay TRN and ,4

the filament of lamp Y of the upper unit of signal SN to terminal C, and bya circuit passing from terminal B through front contact 52 of relay TRN, normal polar contact 536I of relay TRN, back contact 62 of relay ARN and the filament of lamp R of the lower unit of signal SN to terminal C. The display of this aspect by signal SN indicates thatone block is clear between its associated section and the next occupied block. Also, the rails of section M-N are supplied with unidirectional current of normal polarity over front contacts 5 and I of relay TRN; and since relay TRZN is energized with current of normal polarity and relay ARN is redisplay this indication by an energizing circuit for lamp Y of the upper unit of signal SM which may be traced from terminal B through back contact 43 of relay BRM, front contact 49 of relay TRM, normal polar contact -60 of relay TRM and the filament of lamp Y of the upper unit of signal SM to terminal C, and by a circuit passing from terminal B through front contact 52 of relay TRM, normal polar contact 53-6l of relayTRM, front contact H of relay ARM, reverse polar contact "-13 of relay ARM and the filament of lamp Y of the lower unit of signal SM to terminal C. The yellow over yellow aspect displayed by signal SM indicates that two blocks are clear between its associated section and the next occupied block.

Under the above-assumed conditions, unidirectional track circuit current of normal polarity is supplied to the rails of section L-M to energize relay TRL in its normal direction, and current ARM, front contact 18 of relay ARM, normal polar contact 1056 of relay TRM, front contact 51 of relay TRM and primary winding 9 of contact 49 of relay TRL, normal polar contact leased, relay ARM of section MN is energized I,

with 120 code and uninterrupted alternating current, the latter being supplied over a circuit which includes limiting impedance 3 and which extends from terminal BX through impedance 3, back contact 64 of relay ARN, normal polar contact 65-B9 of relay TRN, front contact 61 of relay TRN, the primary winding of relay transformer TN and primary winding 9 of track transformer TTN to terminal CX. Relay CRN accordingly is energized, and 120 code is supplied to the rails of section MN over a circuitpath which shunts impedance 3 and which passes from terminal BX through contact l29al20 of coder CTN, front contact 68 of relay CRN, back contact 69 of relay ARN, normal polar contact 1955 of relay TRN, front contact 51 of relay TRaN and primary winding 9 of transformer TTN to terminal CX. I

With relay TRM energized in its normal direction, relay ARM energized in its reverse direction, and relay BRM released, signal SM of section MN is controlled to display a yellow over yellow indication. Signal SM is caused to track transformer TTM to terminal CX.

In response to relays TRL and ARL both being energized with current of normal polarity and relay BRL being released, signal SL is controlled to display a yellow over green aspect since lamp Y of the upper unit of signal SL is energized over a circuit which may be traced from terminal B through back contact 43 of relay BRL, front Ell-+69 of relay TRL and the filament of lamp Y of the upper unit of signal SL to terminal C, and lamp G of the'lower unit of signal SL is energized over a circuit passing from terminal B through front contact 52 of relay TRL, normal polar contact 536l of .relay TRL, front contact H of relay ARL, normal polar contact 12--'|9 of relay ARL, backcontact 80 of relay BRL and the filament of lamp G of the lower unit of signal SL to terminal C. The display of the yellow over green aspect by signal SL denotes that there are three unoccupied sections between its I associated section and the next occupied section.

-With relays TRL'and ARL energized by ourrent of normal polarity and withrelay BRL released, the corresponding relays TRK and ARK are both energized by current of normal polarity while relay BRK is energized by current of reverse polarity. I 7 v The rails of section K-L are supplied with both uninterrupted alternating current and with alternating current coded at the code rate, the former being supplied over a circuit path which includes limiting impedance 3 and which extends from terminal BX through impedance 3, back contact 8| of relay BRL, normal polar contact 8 382 of relay ARLffront contact 84 of relay ARL, normal polar contact 65-66 of relay TRL, front contact 61 of relay TRL, the primary winding of relay transformer '11., and primary winding 9 of'track transformer TTL to terminal CX. Since relay CRL is energized, -180 code is supplied to the rails of section K-L over a circuit path whichat times shunts impedance 3 and which extends from terminal BX through contact Na-480 of coder CTL, front contact 85 of relay CRL, back contact 80 of relay BRL, normal polar contact 8ITl of relay ARL, front con tact 78 of relay ARL, normal polar contact 10-56 of relay 'IRL, front contact 51 of relay TRL and primary winding 9 of transformer TTL to terminal CX.

When relays TRK and ARK are energized by current of normal polarity and relay BRK is energized by current of reverse polarity, signal SK associated with section Ke-L is controlled to display its green over yellow indication by an obvious circuit for lamp G of the upper unit of that signal completed at front contact 88 of relay BRK, and a circuit which extends from terminal B through front contact 52 of relay TRK, normal polar contact 53-61 of relay TRK, front contact ll of relay ARK, normal polar contact 72-79 of relay ARK, front contact 89 of relay BRK, reverse polar contact 909! of relay BRK and the filament of lamp Y of the lower unit of signal SK to terminal C. The display of this aspect indicates that there are four unoccupied sections in advance of the associated section. Under the assumed conditions, the rails of section J-K are supplied with unidirectional trackway current of normal polarity over front contacts 5 and 1 of relay TRK, and relays ARJ and BRJ are both supplied over their respective line circuits with current of normal polarity so that as a result relays TRJ, ARJ and BRJ are all energized in their respective normal directions. In addition, the rails of section JK are supplied with 180 code over a circuit which may be traced from terminal BX through contact l80a-l80 of coder CTK, front contact 93 of relay BRK, normal polar contact 81-41 of relay ARK, front contact 78 of relay ARK, normal polar contact l56 of relay TRK, front contact of relay TRK and primary winding 9 of track transformer TTK to terminal CX.

With the traffic controlled relays TRJ, ARJ and BRJ associated with section JK all energized with current of normal polarity, as pointed out hereinbefore, signal SJ is controlled to display a green over green indication, the green lamp G of the upper unit of this signal being energized over an obvious circuit including front contact 88 of relay BRJ and the green lamp G of the lower unit of signal SJ being energized over a circuit extending from terminal B through front contact 52 of relay TRJ, normal polar contact 53--6I of'relay TRJ, front contact H of relay ARJ, normal polar contact 12-19 of relay ARJ, front contact 89 of relay BRJ, normal polar contact 90-94 of relay BRJ and the filament of lamp G of the lower unit of signal SJ to terminal C. The display of the green over green aspect by signal SJ indicates that at least the next six successive blocks in advance of such signal are unoccupied.

The rails of the section next in the rear of section JK are supplied with unidirectional track circuit current of normal polarity in the manner previously described, and also are supplied with 180 code over a circuit similar to that traced whereby the rails of section JK are supplied with the corresponding code. In addition, the circuits over which currents of normal polarity are supplied to the AR and BR relays of the rear section are completed at the various front and polar contacts of relays TRJ, ARJ and BRJ.

From the foregoing, it is readily apparent that I have provided novel and improved trackway apparatus for controlling the aspects displayed by wayside signals in accordance with traflic conditions six blocks in advance, thereby providing a six-block, seven-indication wayside signal system. In addition, the wayside apparatus embodying my invention also controls the supply of alternating current to the train-shuntable track circuits of the several sections in such manner that the rails of the sections are at times supplied with track circuit current which is coded at one or another of a plurality of code rates, and at other times are supplied with both coded and uninterrupted or non-coded alternating current.

In connection with the trackway apparatus represented in Figs. lA-lD, inclusive, and hereinbefore described, it is contemplated to employ train-carried apparatus adapted to inductively pick up energy from the rails of the trackway and selectively control a train-carried governing device in response to the rate at which such picked-up energy is coded and to the presence and absence of the uninterrupted component of alternating energy in the track rails.

A preferred form of train-carried apparatus embodying my invention and adapted to be employed in connection with the trackway apparatus illustrated in Figs. 1A to 1D, inclusive, is shown in Fig. 2. Referring now to Fig. 2, the usual train-carried receiver is represented by the two coils 98 and 99 which are disposed in inductive relation with rails I and la, respectively, of the trackway and are connected in series in such manner that voltages induced therein in response to alternating current flowing in opposite instantaneous directions in the two rails are additive. Coils 98 and 99 are carried by the locomotive in front of its leading Wheels as is the customary practice, and such coils are connected through the usual amplifier A to supply energy to a circuit which includes the winding of a code following relay CDR later to be referred to, and the primary winding IOI of a transformer I00 having its secondary winding I02 connected to a polarized master relay MR. When alternating current is inductively received by the coils 98-and 99 from the'trackway, energy is caused to be supplied from amplifier A to transformer I00, and at the start of such energy an impulse of electromotive force of one relative polarity is induced in secondary winding I02 of transformer I00 and is supplied to relay MR, and at an interruption of such energy an impulse of electromotive force of the opposite relative polarity is supplied to the relay MR. The relay MR is responsive to the polarity of current supplied thereto and it follows that when alternating current received by the coils 98 and 99 is periodically varied or coded, relay MR is operated to close its respective reverse and normal contacts |03'l04 and |03-l05 alternately at a rate which corresponds to the rate at which the alternating track circuit current is coded.

Associated with master relay MR is the usual decoding transformer DT comprising a center tapped primary I06 having a first portion thereof supplied in one direction with unidirectional current over reverse contact I 03-404 of relay MR and having its remaining portion thereof supplied in the other direction with unidirectional current over normal contact [03-105 of relay MR, whereby there is simulated the transformer action of alternating current having a frequency H corresp ng to the rate at which the conta t of relay MR alternately are closed. A secondary I01 of transformer DT supplies energy to a group of decoding relays comprising a code detecting relay H and two code selecting relays AJ and BJ, the supply of energy to relay H being first rectified by a rectifier I08 and the supply of energy to the latter two relays being transmitted through decoding units DUI80 and DU-I20, respectively. The details of construction of the decoding units above referred to are not shown in the drawing, but theseunits usually comprise a rectifier and a reactor condenser tuning unit tuned to resonance at a frequency corresponding to the I80 and the I20 codes, respectively, whereby relay AJ is effectively energized and is picked up when and only when relay MR is re.- sponding to I code received from the trackway, and relay BJ is effectively energized andis picked up when and only when relay MR is re-- sponding to at least I code received from the trackway. The code detecting relay H is responsive to the supply of energy from transformer DT coded at any one of the code rates and hence is energized whenever relay MR is responding to coded current received from the trackway.

The code following relay CDR above referred to is provided to detect the presence of the noncoded or uninterrupted component of alternating current which at times is present during the off intervals of the coded alternating track circuit current supplied to the trackway and received by the coils 98 and 99. During the interval that coded current only is being supplied to the rails of the trackway and is being picked up by the coils 98 and 99, the energy supplied from amplifier A to relays MR and CDR varies between a given maximum value during the on period of the code and a given minimum value during the off period of the code, which minimum value is below the release value of relay CDR. In response to the on portions of such current, relay MR is operated to its normal position and relay CDR is effectively energized and picked up, and in response to the off portions of such coded energy, relayMR i operated to its reverse position and relay CDR is deenergized and released. The alternate energization and deenergization of relay CDR in response to coded energy received from the rails I and la causes a relay CPR to be energized through the medium of decoding transformer DTI having a center-- tapped primary winding I39 supplied with energy alternately over front contact I40 and back contact I 4| of relay CDR and supplying energy from a center-tapped secondary winding I42 to relay CPR over contacts I43 and I44 of relay CDR, which contacts operate, as is readily apparent from an inspection of the drawing, to supply substantially unidirectional current to relay CPR from winding I42. When, however, the uninterrupted component of alternating current is present during the off periods of the coded alternating track circuit current, the minimum value of the energy supplied from amplifier A to relays MR and CDR is increased. Relay MIR continues to follow the coded portions of such energy since each increase or decrease in energy supplied to transformer I00 causes relay MR to operate its polar contact member, but code following relay CDR is held continuously energized when uninterrupted current is present in the track circuit during the off intervals of the coded current, since the minimum value of the current supplied under such conditions by amplifierA is above the release level of the relay. Relay CPR is caused to release when relay CDR is held continuously energized by the uninterrupted component of alternating current in the track circuit since under such conditions no current, is supplied from winding I42 of transformer DTI to relay CPR.- Hence relay CPR functions to detect the presence or absence of the uninterrupted component of alternating trackway energy.v

The decoding relays H, AJ and BJ, and relay CPR cooperate to selectively control the operation. of a train-carried governing device,illustrated in Fig. 2 as a seven-indication cab signal CS. The manner in which the operation of signal CS is controlled by the train-carried apparatus embodying my invention will be pointed out hereinafter when the operation of the traincarried apparatus is described for each different form of alternating current supplied to the trackway. At this time, however, it should be pointed out that the usual audible indicator, acknowledging switch and group of acknowledging relays one for each cab signal indication except the least restricted or green over green indication, may be incorporated in the customary manner in the apparatus illustrated in Fig. 2. Such apparatus has been omitted from the drawing and the description, however, since it is wellknown and it is believed that the modifications required to adapt the standard apparatus customarily employed to the apparatus of Fig. 2 will readily be apparent to those skilled in the art.

I shall assume that, with the apparatus of Figs.

. IA to ID, inclusive, in the condition in which it is illustrated wherein train W occupies the section in advance of section OP, a train equipped with train-carried apparatus similar to that shown in Fig. 2 and hereinbefore described, enters section J-K from the left so that the coils 98 and 99 inductively pick up I code alternating track circuit current present in the rails of the section. Under the above assumed conditions, the I80 code current inductively picked up from the rails of the trackway by coils 98 and 99 and supplied through amplifier A torelays MR and CDR causes both relays to follow each code period of the received current, and as a result decoding relay AJ is picked up due to relay MR responding to I80 code, and relay CPR is picked up in response to relay CDR responding to the coded energy. Signal CS accordingly is caused to display its green over green indication by a circuit which extends from terminal B through front contact III of relay CPR, front contact II2 of relay AJ, the filament of indication unit G/G of signal CS, front contact II3 of relay AJ and front contact I I4 of relay CPR to terminal C. This aspect displayed by signal CS denotes that five blocks, at least, in advance of the block being traversed are unoccupied. Under the assumed conditions of code in the trackway, it is immaterial whether relays BJ and H are energized or deenergized since these relays do not at this time exert any control over cab signal CS. However, if the decoding units DU are high-pass filters, relay BJ will be picked up, as shown in Fig. 2, in response to the received I80 code. Relay I-I also is picked up, as shown, in response to the I80 code since such relay is energized whenever relay MR follows coded current received which are supplied to the two track rails of such section in series, then relay CPR is released by reason of the fact that code following relay CDR is held steadily energized since the minimum value of the energy supplied through amplifier A now exceeds the release value of relay CDR, and as a result signal CS is caused to display its green over yellow indication over a circuit which extends from terminal B through back contact H of relay CPR, front contact ill of relay AJ, the filament of signal indication unit G/Y of signal CS, front contact II! of relay AJ and back contact N3 of relay CPR to terminal C. This aspect of signal CS denotes that the fifth block in advance of the block being traversed is occupied by a train and the intervening blocks are unoccupied.

The purpose of providing the track circuit current transmitting apparatus of the sections of Figs. 1A to 1D with checking relays CR will now be evident, since it is apparent that a less restrictive indication is caused to be displayed when the train-carried apparatus responds, only to coded alternating trackway energy than is caused to be displayed by such apparatus responding to the presence of both coded and noncoded trackway energy in the rails of the section. In order, therefore, to check such more restrictive indication and to insure that a less restrictive indication cannot be displayed in the event the trackway apparatus is conditioned to supply both coded and non-coded alternating track circuit current to the rails of a section, the supply of coded current is caused to be carried over front contacts of the associated checking relay held energized by the supply of noninterrupted current to the track rails. It follows that if for any reason there is a failure of the supply of non-coded current to the track'rails of a section, then the supply of coded current also is cut off from the rails and as a result the train-carried apparatus is caused, as will appear presently, to control signal CS to its most restrictive indication. 1

When the train enters section L-M and picks up I251 code from the rails of this section, relays H, BJ and CPR are picked up, but relay AJ is released. Signal CS now is caused to display its yellow over green aspect over a circuit which extends from terminal B through front contact III of relay CPR. back contact I2I of relay AJ, front contact in of relay BJ, the filament of indicationunit Y/G of signal CS, front contact I23 of relay BJ, back contact I24 of relay AJ and front contact IM of relay CPR to terminal C. The aspect displayed by signal CS while the train traverses section LM denotes that the fourth block in advance of section L-M is occupied and the intervening blocks are unoccupied.

In the event that the train enters section M-N so that the train-carried receiving coils 98 and 99 pick up both the 120 code and the uninterrupted alternating current which are supplied to the rails of such section, relays H and BJ are picked up, relays AJ and CPR are released, and signal CS is controlled to display a yellow over yellow aspect by a circuit which may be traced from terminal B through back contact II5 of relay CPR, back contact I25 of relay AJ, front contact I26 of relay BJ, the filament of indication unit Y/Y of signal CS, front contact I27 of relay BJ, back contact I28 of relay AJ and back contact II8 of relay CPR to terminal C. The indication displayed by signal CS under the above assumed conditions indicates that the third block in advance of the section being traversed is occupied and that the two intervening blocks are unoccupied.

When the train is traversing section N-O and the coils 98 and 99 pick up 15 code from the rails of such section, relays H and CPR are picked up but relays BJ and AJ are released, and signal CS accordingly is caused to display its yellow over red aspect over a circuit which may be traced from terminal B through front contact III of relay CPR, back contact I2I of relay AJ, back contact I29 of relay BJ, front contact I30 of relay H, the filament of indication unit Y/R of cab signal CS, front contact I3I of relay H, back contact I32 of relay BJ, back contact I24 of relay AJ, and front contact II4 of relay CPR to terminal C. Signal CS in display ing a yellow over red aspect denotes that the second block in advance of the block being traversed is occupied and the block next in advance is unoccupied.

If, now, the train is traversing section 0-? so that the coils 98 and 99 pick up from the rails of such section both the '75 code and the uninterrupted alternating current that are supplied to such section, then relay H is picked up but relays BJ, AJ and CPR are released, and as a result signal CS displays its red over yellow aspect by a circuit which extends from terminal B through back contact II5 of relay CPR, back contact I25 of relay AJ, back contact I33 of relay BJ, front contact I34 of relay H, the filament of indication unit R/Y of cab signal CS, front contact I35 of relay H, back contact I36 of relay BJ, back contact I28 of relay AJ, and back contact II8 of relay CPR to terminal C. The display of this aspect by signal CS indicates that the section next in advance of the section being traversed by the train is occupied.

Whenever the train equipped with train-carried apparatus shown in Fig. 2 is following another train in a section, then the alternating trackway energy is shunted away from such following train and consequently substantially no energy is picked up by the coils 98 and 99 from the trackway so that as a result relays AJ, BJ, H and CPR are released and signal CS displays a red over red indication over a circuit which extends from terminal B through back contact H5 of relay CPR, back contact I25 of relay AJ, back contact I33 of relay BJ, back contact I3? of relay H, the filament of indication unit R/R of signal CS, back contact I38 of relay H, back contact I36 of relay BJ, back contact I28 of relay AJ and back contact II8 of relay CPR to terminal C. This red over red indication is displayed by the cab signal CS when no energy is received from the track rails of its associated section, and represents the most restrictive trafiic condition such as is obtained when the section being traversed is occupied by another train, or when there is a failure of the track rails or of the track circuit current transmitting apparatus.

From the foregoing description, it is readily apparent that the apparatus illustrated in Fig. 2 and hereinbefore described provides novel and improved railway traffic controlling apparatus wherein the customary few individual code rates of track circuit current are employed at times with and at other times without an additional uninterrupted component of track circuit current to selectively control a multiple indication train-carried governing device. It is evident that by providing means to detect the presence of the different controls according as such uninterrupted alternating current i or is not present.

It follows, therefore, that apparatus embodying my invention provides means for increasing the number of indications that may be controlled by. the customary few code rates.

In this connection, it should be pointed out that although my invention has been described in connection with a system in which three different rates .of coding. are employed, it is to be understood that my invention contemplates the use of any suitable or desired number of such rates each of which may be used either with or without a non-coded or uninterrupted component of current, thereby .providinga number of controlsdouble that which may be obtained by using suchcodes individually. Also, it is to be understood that although the apparatus, of Fig. 2 is illustrated as a seven-indication cab signaling system, such apparatus might be converted into a system providing, for example, six or five indications by doing away with such of the indications of signal CS and their associated control circuits as'are unnecessary in the particular system desired.

It is,-of course, to be understood that the decoding means shown in Fig. 2 applied to a traincarried signal system, may if desired be. incorporated into a wayside signal system provided for a stretch of track supplied at times with coded current 'and at other times supplied with both cod-ed current and with. an additional component of uninterrupted track circuit current supplied during-the off intervals of the coded current for selectively controlling wayside signals and for controlling the supply of'both coded and noncoded track circuit current to the rails of. the

trackwa-y.

In Fig-.3 is .illustrateda modified arrangement of the wayside apparatus shown in Figs. .lAto- 1D for. incorporating the two rails of a trackway into. a. series or train-shuntable track circuit whichis supplied with track circuit current coded andwhichattimes is. additionally supplied with nonI-codedor. uninterrupted alternating currenttoincrease 'thenumber of functions controlled by such coded current.

In Fig. 3, an approach control relay ACE is employed to control or modify in accordance with trafiic conditions in a track'section, the supply of track. circuitcurrent that is supplied to therails of such section. Relay ACR might, forexamplebe incorporated into wayside apparatus. similar to that shown in Figs. 1A to 1D, and in which eventthe supply of both coded and non-coded alternating track circuit current might'be controlled by relay ACR since such track circuit current is employed solely to control train-carried apparatus such as is shown in Fig. 2, hence such track circuit current need be supplied to the railsv of a section only when such section is occupied. Relay ACR might also be employed with other types of wayside apparatus to modify the form of track circuit current that is supplied to the rails of a section for controlling a wayside signal during the intervals that such section is unoccupied, and which curpair of insulatedjointsto enable the two track cab signal during the intervalsjof. occupancy of the. section. 'This latter use ofv relay ACR is illustrated in 3, wherein. relay ACE is shown incorporatedinto a signal system provided for a stretch of electrified trackway.

Referring now toFig. 3, the track rails l and la arev divided by insulated joints 2 into successive' adjoining track sections, one section, D-E,

being shown complete in the drawing, and impedance bonds I50Qare provided one for each rails to form a. portion of the return path for the electric propulsion current. The bonds I50 are of the usual construction which permits electrical propulsion current flowing in the two track rails. in parallel tov be transferred around insulated joints 2,. bu t' which bonds prevent similar transfer around joints 2 of track circuit or signaling current flowing through the two track rails, in series.

The rails of each of, the sections of track of Fig. 3 are connected in a series or train-shuntable track circuit formed by, coupling a code responsive track relay, designated'by the reference character TR' with asuitably distinguishing suf-,

fix, to receive from the track'rails at one end of a section track circuit energy'supplied 'to the rails at the other. end of the section from a suitcircuit is provided forsection,D E of Fig. 3

able source of current. For example, a track by connecting, in' series with the usual current limiting impedance l5l, secondary winding 8 of track. transformer T'Ililv across the rails of the .section adjacent exit end E, and by connecting; track relay TRD across the track rails adjacent entrance end D of sectionjD-E. As shown, relay 'I'RD'is an alternating current relay responsive to the coded alternating current that is supplied to primary winding 9v of transformer TTE over one,

or. another. of a plurality of. circuits shortlyto be traced, but it is. to be understood, of course,

. current relay to the track rails through the methat a'direct current code responsive trackv relay might be employed in the place of the alternating current relay 'ITRD by coupling the direct diurn of the usual relay transformer and a fullwave rectifienf I I Each of the sections of track of. Fig. 3 is provided with decoding apparatus operated by.

the -,assoc'iated code following track relay TR and effective to control the. supply of, track circuit current tothe rails' of the section next in'the' rear, and also controlling the aspects displayed 55, by the wayside signal provided for the associated section, The wayside signals employed inthe signal system of'Fig..3,ma y take any one of many well-known forms, but as shown such signals are four-indication color light signaIs'designated by the reference character S with a distinguishing suflix, having a, fjclear signal unit G, an .approach'medium signal unit Y/G, an approach signal unit Y, and a stop signal unit R.

The. decoding apparatus associated with each I. track relay TRof'FigB includes the. usual decoding relays and lock-out relays arranged in the customary and well-known manner to supply coded alternating current to the rails of the sectionnext in the rear, but supplying to such rails non-coded alternating current in the event that currentfrom such rear section leaks forwardlyover a defe'ctiveinsulated joint into the adjoining'advance section to energize falsely the track/relay of such advance section. I shall de-, scribe such decoding apparatus only briefly since the particular arrangement thereof forms no part of my present invention. This decoding apparatus, as represented in Fig. 3 associated with track relay TRE of the section next in advance of section DE, includes the usual code selecting relays AJ E and BJ E connected by an obvious circuit including decoding units DUIBIl and DUI20, respectively, to a source of current alternately over a front and a back contact of relay TRE; two lock-out relays FSE and BSE, one relay FSE being energized over a front contact of relay TRE and the other relay BSE being energized over a back contact of relay TRE anda front contact of relay FSE; and a code detecting relay HE provided with a pick-up circuit extending from terminal B through front contact I55 of relay TRE, back contact I56 of relay HE, front contact I51 of relay BSE, and the winding of relay HE to terminal C. Relay HE is also provided with a stick circuit passing from terminal B through front contact I58 of relay HE, front contact I5! of relay BSE and the winding of relay HE to terminal C.

The decoding apparatus just described functions to set up or establish one or another of the usual plurality of circuits over which track circuit current is supplied to primary winding 9 of track transformer TTE, and in accordance with my invention, the supply of current to such transformer is additionally controlled by the previously mentioned approach control relay ACR. Relay ACR, as shown, is energized over an obvious circuit controlled by track relay TRD of section DE and completed at front contact I60 of a relay FSD, which latter relay may be one of the lock-out relays incorporated in the decoding apparatus (not shown in Fig. 3 but substantially similar to the decoding apparatus provided for relay TRE) of section DE.

When relay ACR is picked up due to its associated track relay TRD following coded energy received from the rails of section D.-E, the decoding apparatus associated with track relay TRE is conditioned to set up or establish, in accordance with. traffic conditions in and in advance of section D-E, one or another of the plurality of circuits over which track circuit current is supplied to track transformer TTE. A first of such plurality of circuits may be traced from terminal BX through contact I8Il-I8Ila of coderCTE, front contact I63 of relay BJE, front contact I64 of relay HE, front contact I65 of relay BSE, front contact I66 of relay FSE, back contact I61 of a checking relay CRE, to be referred to later, front contact I68 of relay ACR, impedance I69 and primary winding 9 of transformer TTE to terminal CX. It is readily apparent that current supplied to transformer TTE over the above traced circuit is coded at 180 times per minute. A second of such plurality of circuits extends from terminal BX through contact I2lll26a of coder CTE, backcontact I10 of relay'B-J E and then extending from front contact I64 of relay HE to winding 9 of transformer TTE and mrminal CX through a circuit path which corresponds to the circuit path just traced for IBI! code from front contact I64 of relay HE, and it follows that current supplied to transformer TTE over this second of the plurality of circuits is coded atthe 120 code rate. Current coded at the -'75 code rate is supplied to transformer TTE due to the action of contact I5-I5a of coder C'IE, which contact is included in a third circuit which passes from terminal BX through back contact III of relay BSE, back contact I12 of relay FSE, contact I5a-'l5 of coder CTE, back contact I6'I of relay CRE, front contact I63 of relay ACR, impedance I69 and primary winding 9 of transformer TTE to terminal CX. A fourth of such plurality of circuits may be traced from terminal BX through back contact I II of relay BSE, front contact I66 of relay FSE, back contact I61 of relay CRE, front contact IE8 of relay ACR, impedance I69 and primary winding 9 of transformer TTE to terminal CX.

It is readily apparent from an inspection of Fig. 3 that if relay CRE is picked up to close front contact I M and relay ACE is released to close back contact I15, and one or another of the above traced plurality of circuits is completed at all other points, then such circuit is effective to supply track circuit current to transformer TTE in the same manner as if relay CRE were released and relay ACR picked up. In other words, each of the plurality of circuits above traced is completed over one or the other of two alternate circuit paths, a first path including back contact l6! of relay CRE and front contact I68 of relay ACE, and the second path including front contact I14 of relay CRE and back contact I15 of relay ACR. Each of the plurality of circuits above mentioned in conditioned to be completed over the first of the two alternate paths when relay ACE is picked up due to section DE being unoccupied, and such circuits are conditioned to be completed over the second of the two alternate paths whenever relay ACE is released in response to a train in section DE shunting the track circuit current away from relay TRD.

When relay ACE is released, uninterrupted or non-coded alternating current is supplied to transformer TTE over a circuit extending from terminal BX through the primary winding of a relay transformer TE, back contact I6I of relay ACR, impedance I62 and primary winding 9 of transformer TTE to terminal CX. This supply of current through the primary winding of relay transformer TE causes an electromotive force to be induced in the secondary winding of transformer TE, and this induced electromotive force is rectified by a rectifier RTE into and is supplied to relay CRE as unidirectional current which energizes relay CRE and causes it to pick up. It follows, therefore, that when relay ACR is released and uninterrupted alternating current is supplied over back contact I6I of relay ACR to transformer TTE, relay CRE is picked up to condition each of the previously mentioned plurality of circuits to be completed over the second of the two alternate paths.

In describing the operation of the apparatus represented in Fig. 3, I shall assume that such apparatus is employed to indicate the presence along the trackway of fixed hazards, such as the hazard indicated in Fig. 3 and designated by the reference character Z. Such hazards may, for example, comprise a curve, bridge, fill, out, tun nel, or the like. Those sections of track, therefore, that include one or more of such track hazards accordingly are provided with apparatus similar to that shown in Fig. 3 and capable of controlling the supply of track circuit current in such manner that coded current normally is supplied to the rails of the section but uninterrupted or non-coded current is at times supplied in addition to such coded current to the rails of the section. Other sections of track free from fixed hazards are preferably provided with track circuit apparatus of the usual arrangement capable of supplying only coded track circuit current, with uninterrupted track circuit current being at times substituted'for, but not supplied in addition to, the coded track circuit current, for indicating a failure of an insulated rail joint.

With a stretch of trackway equipped with apparatus in the manner just described, it is readily apparent that coded track circuit current is supplied normally to the rails of each of the track sections, and if such sections are unoccupied, the associated code responsive track relays are caused to follow the coded current to operate the associated decoding apparatus and selectively control the associated wayside signals in accordance with the code rate of the applied track circuit current. For. example, if the rails of the section next in advance of section picked up by the train. When such train :occupies sections free from track hazards, coded track coded at the I88, I20 or 15 code rate.

D-E are supplied with I88 code, relay TRE is caused to operate and relay AJE is picked up to complete at front contact I82 an obvious circuit for lamp G of signal SE. Relays FSE,BSE, 'HE and 'BJE also are picked up, as shown in Fig. 3, and as a result I88 code is supplied to the rails of section DE over the previously traced first circuit over which transformer TTE is supplied with current.

When I28 code is supplied to the rails of the section in advance of section DE, relay AJE is released but relays FSE, BSE, HE and BJE are picked up. Signal SE is caused to display its yellow over green aspect over a circuit extending from terminal B through back contact I83 of relay AJE, front contact I84 of relay BJE and the filament of unit Y/G of signal SE to terminal C; and the rails of section DE are supplied with I80 code track circuit current since the previously traced first circuit for transformer TTE is still completed.

In the event that code is received by relay TRE from the rails of its associated section, re-

lays AJE and BJE are released but relays FSE,

BSE and HE are picked up. As a result, signal SE is caused to display its yellow aspect over a circuit extending from terminal B through back contact I83 of relay AJE, back contact I85 of relay BJE, front contact I86 of relay HE and the filament of unitY of signal SE to terminal C. The rails of section DE are supplied at this time with I28 code track circuit current over the previously traced second circuit of transformer TTE.

If, however, relay 'I'RE is shunted by a train in the associatedsection, then relays FSE, BSE, HE, BJE and AJE are allreleased and signal SE is caused to display its red aspect over a circuit passing from. terminal B through back contact I 83 of relay AJE, back contact I85 of relay BJE, back contact I81 of relay HE and the filament'of unit R of signal SE to terminal C. The rails of section DE are supplied with 15 code at this time over the previously traced third circuit of transformer TIE.

From the foregoing description, it can be seen that the supply of coded track circuit current to a track section is controlled by traffic conditions in advance, and that such current is utilized to selectively control the wayside signals associated with the trackway.

If, now, a train equipped with train-carried apparatus embodying my inventionand similar, for example, to the apparatus represented in Fig. 2, operates along the stretch of trackway represented in Fig. 3, the track circuit current'that is supplied to the rails of the trackway will be If, however, such train occupies a track section which includes a fixed track hazard, such,.

for example, as section DE shown in Fig.8, then the train in the section will cause the associated approach control relay ACR to be released, whereupon non-coded or uninterrupted track circuit current will be supplied to the rails of the section in addition to the coded track circuit current, as pointed out hereinbefore. This coded and non-coded current will of course be picked up by the train in the section, and will cause the train-carriedapparatus of Fig. 2 to control cab signal CS to its green over yellow (Gi/Y), yellow over yellow (Y/Y) or red over yellow (R/Y) aspect according as the codedcomponent of such current is coded at the I80, I20 0r I5 code rate, :as explained hereinbefore'. It

follows, therefore, that the apparatus of Fig. 3

incorporates means for controlling wayside signals by .coded track circuit current, and capable of causing distinctively different cab signal indications to be displayed according as the section occupied by a train is or is not free from fixed track hazards. It is, of course, obvious that the distinctive cab signal aspects, provided on trains in sections having fixed "track hazards, function not only to indicate the presence of the hazard but also toindicate traffic conditions in advance.

It is to be understood, of course, that the traincarried apparatus represented in Fig. 2 embodying my invention, might be'modified to provide a supplemental indication which becomes illuminated only when both coded and non-coded current are supplied to the rails of a section. If such modified cab signal apparatus were employed, the cab signal could then be modified to provide only the usual number of signal indications, say the four aspects green (G) yellow over g-reen (Y/G), yellow (Y) andred (R), and such aspects, except the red (R), could then be dis- 3 played either without or with the supplemental indication to indicate in'the first'case, trafficconditions in advance and indicating in the second case both traffic conditions in advance and the presence of the fixed hazard'in the section.

trol relay ACR of Fig. 3 is released by a train in an associated section, such relay then functions to supply non-coded current to the rails of the cluding front contact I14 of relay CRE. and back contact I15 of relay ACR. In this manner, there- 7 fore, the supply of non-coded current to'theirails of a section is checked, so that if the apparatus is conditioned to supply both coded and non-' coded current to a section/the supply of non- I coded current must be effective before coded current is supplied also. Accordingly, it can be seen' that non-coded current may be safely utilized together with coded current to control a less restrictive functionthan is controlled by the coded As pointed out previously, when approach con-- rent to be cut off and as a result the section is supplied with no track circuit current. It follows, therefore, that the apparatus represented in Fig. 3 incorporates the usual safeguards requisite in railway signal systems.

Although I have herein shown and described only three forms of railway traffic controlling apparatus embodyin my invention, it is to be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spiritand scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a section of railway track having its two track rails connected in a series or a train-shuntable track circuit, a source of periodic current for said track circuit, means responsive to predetermined conditions for supplying said circuit with current from said source periodically interrupted at one or another of a plurality of rates of coding and for at times additionally supplying to said circuit uninterrupted current from said source, and railway traffic controlling apparatus receiving energy from the rails of said section and selectively controlled in accordance with the rate at which the coded component of current in the track rails is coded and also in accordance with the presence or absence of the uninterrupted component of current in the track rails.

2. In combination, a section of railway track having its two track rails connected in a series or a train-shuntable track circuit, a source of alternating current for said track circuit, means responsive to predetermined conditions for supplying said circuit with current from said source coded at one or another of a plurality of rates of coding and for at times additionally supplying to said circuit non-coded current from said source, and railway trafiic controlling apparatus receiving energy from the rails of said section and selectively controlled in accordance with the rate at which the coded component of current in the track rails is coded and also in accordance with the presence or absence of the non-codedcomponent of current in the track rails.

3. In combination, a section of railway track having its two track rails connected in a series or a train-sh'untable track circuit, a source of alternating current for said track circuit, means responsive to predetermined conditions for supplying said circuit with current from said source coded at one or another of a plurality of rates of coding and for at times additionally supplying to said circuit non-coded current from said source, and railway traffic controlling apparatus inductively receiving energy from the rails of said section and selectively controlled in accordance with the rate at which the coded component of current in the track rails is coded and also in accordance with the presence or absence of the non-coded component of current in the track rails.

4. In combination with a section of railway track having a secondary winding of a track transformer connected across the track rails at one end of said section, a source of alternating current for the primary winding of said track transformer, means responsive to predetermined conditions for supplying said transformer primary winding with current from said source coded at one or another of a plurality of code rates and for at times additionally supplying said.

transformer primary winding with non-coded trackprovided with an insulated track section, a source of alternating current for said section,

means responsive to traffic conditions on said stretch for supplying the rails of said section at times with current from said source coded at one or another of a plurality of code rates and for supplying said track rails at other times with non-coded current from said source, a checking relay controlled by the supply of said non-coded current to said track rails, and means controlled by said checking relay for supplying said track "rails with current from said source coded at one or another of said plurality of code rates in accordance with traflic conditions on said stretch. 6. In combination with a stretch of railway track provided with an insulated track section having a secondary winding of a track transformer connected across the rails at one end of said section, a source of alternating current for the primary winding of said transformer, trafilc controlled means for supplying said transformer primary winding at times with current from said source coded at one or another of a plurality of rates of coding and for supplying said transformer primary winding at other times with noncoded current from said source, a checking relay inductively controlled by the supply of said non-coded current to said transformer primary winding, and means controlled by said checking relay for conditioning said traffic controlled means at said other times to additionally supply said transformer primary winding with current from said source coded at one or another of said plurality of code rates in accordance with traffic conditions on said stretch.

7. In combination with a stretch of railway track divided into a plurality of successive adjoining track sections each having a polarized track relay controlling the polarity of unidirectional current supplied to the track rails of the section next in the rear, a plurality of polarized line relays two for each of said sections, circuit means controlled by the track and line relays of each section for controlling the polarity of energization of the line relays of the section next in the rear, a plurality of wayside signals one for each of said track sections, means controlled by the track and line relays of each sectionfor selectively controlling the associated wayside signal, and other means controlled by the track and line relays of each section for supplying the rails of the section next in the rear at times with alternating current coded at one or another of a plurality of code rates and supplying such track rails at other times with both coded alternating current and non-coded alternating current.

8. In combination with a stretch of railway track divided into a plurality of successive adjoining track sections each having a polarized track relay controlling the polarity of unidirectional current supplied to the track rails of the section next in the rear, a plurality of polarized line relays two for each of said sections, circuit means controlled by the track and line relays of each section for controlling the polarity of enaesaaa ergization of the line-relays-ofthe section next inthe rear, .apluralitylof wayside signals one foreach of said track. sections, means controlled by the ,track and line relays of each section for controlling the associated waysidesignah-other means controlled by the track and line relays of each section for supplying the track rails of the section next in the rear at times with alternata ing current coded at one or another of a plurality of code rates in accordance with traffic conditions on said stretch and at other times jsupplying noncoded alternating current to said track rails, a checking. relay for each section energized by the supply of non-coded alternating tioning said other means 'tofbe' effective at. said other times to additionally supply the. rails of the section next in the rear with current coded at one or the otherv o'f-said' plurality of code rates in accordance with trafiic conditions on .said stretch. i f

9. The combination with a stretch of railway track attimes supplied-with alternating current coded at one or another of a plurality of rates of coding and at other times supplied with both coded and non-coded alternating current, of receiving means for inductively receiving energy from the rails of said stretch, decoding means selectively controlled by energy supplied from said receiving means in accordance with the code rate of the coded component of such energy, other means controlled by energy supplied from said receiving means and responsive to the coding of such energy only during the absence from the track rails of the said non-coded alternating current, and trafiic controlling means selectively controlled by said decoding means and by said other means.

10. The combination with a stretch of railway track supplied with alternating current coded at one or another of a plurality of rates of coding and which at times is additionally supplied with non-coded alternating current, of train-carried receiving means for inductively receiving energy from the rails of said stretch, decoding means selectively controlled by energy supplied from said receiving means in accordance with the code rate of the coded component of such energy, other means controlled by energy supplied from said receiving means and responsive to the coding of such energy only during the absence from the track rails of the said noncoded alternating current, and a train-carried trafic governing device selectively controlled by said decoding means and by said other means.

11. In combination with a receiving means for inductively receiving alternating current from the rails of a trackway, a code responsive relay and the primary winding of a transformer both supplied with current from said receiving means, a code following relay receiving energy from the secondary winding of said transformer, decoding means selectively controlled by said code following relay in accordance with the rate at which said current supplied from said receiving means is varied, other means controlled by operation of said code responsive relay caused by said current supplied from said receiving means varying between predetermined limits, and traflic controlling means selectively controlled by said decoding means and by said other means.

12. In combination with a receiving means for inductively receiving alternating current from the rails of a stretch of vtrackway, a series circuit comprising the winding; ofa: code responsive relay and the. primary winding of a transformer, amplifying means for supplying said series circuit with currentfrom said receiving means, a-code 'following .r elay receiving' energy from the secondarywindingof said transformer, decoding means i selectively controlled by said code following relay inaccordance with the rate at which said current ,supplied from-said amplifying means is varied,

other means controlled by said code responsive relay in response to, said current from said amplisaid other means.

f ying me ns varying between predetermined limits, "and" traflic governing means selectively controlled jointly by said decoding means and -13.'I'n combination, a series circuit comprising the winding ofiacontrolrelay and the primary winding. of a transformer, means receiving energy from therailsqf a trackway for supplying said series circuit with current, said control re- ;laybeing responsive to -variations between pre- 1 determined limits of said current from said receiving means, a code .following relay receiving energy fromthe secondary winding ofsaid transformer, decoding means selectively controlled by said code following relay in accordance .with the rate of variations of said energy from said transformer secondary winding, and traffic governing means selectively controlled by said decoding means and said other means.

14. In combination with means for receiving energy from the rails of a stretch of trackway, a circuit including the winding of a control relay supplied with current from said receiving means, said control relay being responsive to said current within predetermined limits, a code following relay inductively coupled to said circuit, decoding means selectively controlled by said code following relay in accordance with the rate of variations in said current in said circuit, and railway trafiic controlling apparatus selectively controlled jointly by said decoding means and said control relay.

15. In combination with a stretch of railway track provided with an insulated track section, code transmitting means for supplying the rails of said section at times with current coded at one or another of a plurality of code rates in accordance with traflic conditions in advance, an approach control relay controlled by traffic conditions in said section, means controlled by said approach control relay for supplying the rails of said section at other times with non-coded or uninterrupted current, and means controlled by said supply of non-coded current to the rails of said section for conditioning said code transmitting means to supply the rails of said section at said other times with coded current in addition to said non-coded current.

'16. In combination with a stretch of railway track provided with an insulated track section, a code responsive track relay for said section, code transmitting means for supplying the rails of said section at times with current coded at one or another of a plurality of code rates in accordance with trafilc conditions in advance, an approach control relay controlled by said track relay,

means controlled by said approach control relayfor supplying the rails of said section at other times with non-coded or uninterrupted current, and means controlled by said supply of noncoded current to the rails of said section for conditioning said code transmitting means at said to the rails of said section.

17. In combination with a stretch of railway track provided with an insulated track section, a code responsive track relay for said section, code transmitting means for supplying the rails of said section at times with current coded at one or another of a plurality of code rates in accordance with traflic conditions in advance, an approach control relay controlled by said track relay, means controlled by said approach control relay for supplying the rails of said section at other times with non-coded or uninterrupted current, a checking relay controlled by said supply of noncoded current to the rails of said section, and means jointly controlled by said approach control relay and said checking relay for conditioning said code transmitting means to superimpose coded current on said non-coded current.

18. In combination with a section of railway track, code transmitting means for supplying to the rails of said section alternating track circuit current coded at times in a first manner by periodically interrupting the supply of current to the rails and at other times in a second manner I other times to additionally supply coded current by periodically shunting an impedance interposed in the circuit over which current is supplied to the rails, and railway traffic controlling means receiving energy from the rails of said section and selectively responsive both to the code rate of and the manner in which such energy is coded.

19. In combination with a section of railway track, code transmitting means for supplying the rails of said section with alternating track circuit current at times coded in a first manner to comprise on intervals when current of a pre determined magnitude flows separated from each other by ofi intervals when no current flows and at other times coded in a second manner to comprise on intervals of current of said predetermined magnitude separated from each other by off intervals during each of which there is a flow of current of a selected value intermediate said predetermined magnitude and a zero value, and railway traflic controlling means receiving energy from the rails of said section and selectively responsive both to the code rate of and the manner in which such energy is coded.

LESLIE R. ALLISON. 

